Recovery Time Effects Research Articles

The Effect of Recovery Time on Strength Performance Following a High-Intensity Bench Press Workout in Males and Females

To determine the effects of training sessions, involving high-resistance, low-repetition bench press exercise, on strength recovery patterns, as a function of gender and training background. The subjects were 12 athletes (6 males and 6 females) and age-matched college students of both genders (4 males and 4 females). The subjects completed a 3-wk resistance training program involving a bench press exercise, 3 d/wk, to become familiar with the testing procedure. After the completion of the resistance training program, the subjects, on three consecutive weeks, participated in two testing sessions per week, baseline session and recovery session. During the testing sessions, subjects performed five sets of the bench press exercise at 50% to 100% of perceived five repetition maximum (5-RM). Following the weekly baseline sessions, subjects rested during a 4-, 24-, or 48-h recovery period. Strength measurements were estimates of one repetition maximum (1-RM), using equivalent percentages for the number of repetitions completed by the subject at the perceived 5-RM effort of the bench press exercise. The full-factorial ANOVA model revealed a Gender by Recovery Period by Testing Session interaction effect, F(2, 32) = 10.65; P < .05. Among male subjects, decreases in estimated 1-RM were detected at the 4- and 24-h recovery times. There were no differences in muscle strength among the female subjects, regardless of recovery time. For bench press exercises, using different recovery times of 48 h for males and 4 h for females may optimize strength development as a function of gender.

Completing A Prior Set Of Hang Cleans Does Not Improve The Performance In The Vertical Jump Irrespective Of The Length Of The Recovery Period

Abstract It has been suggested that acute increases in the power output during explosive movements can occur by the prior execution of high intensity resistance exercises. This phenomenon is called Post Activation Potentiation (PAP). One critical factor that is involved in PAP is the length of the recovery period between the intervention and the performance. The isolation of the recovery time as the independent variable has not been successfully achieved previously and there is a need to determine its net effects on the dependent variables measured in PAP studies. To systematically vary the length of the recovery period post hang clean in order to determine the effects of recovery time on performance. Twelve strength-trained male track and field athletes (22.42 ± 5.66 yrs, 1.80 ± 0.07 m, 80.3 ± 8.72 kg) completed 8 randomised protocols with each of them consisting of a structured warm-up, 3 pre standing countermovement vertical jumps, 3 reps of hang cleans set at 90% of 1RM, a variable seated rest and 3 post vertical jumps. The variable rest was set at 0 (T0), 1 (T1), 2 (T2), 3 (T3), 4 (T4), 5 (T5) and 6 (T6) minutes recovery from the hang cleans while a control (C) protocol without the hang clean intervention was also employed. The vertical jumps were performed on a force platform (1000 Hz) and several mechanical variables (e.g. peak power) as well as the jump performance (jump height) were calculated from the force-time curves. A two factor within subjects ANOVA showed no significant changes in any of the mechanical variables in terms of either factor (hang clean, recovery time) or hang clean × recovery time interaction. Regarding the jump height, the post performance remained unchanged for C, T1, T4, T5 and T6 whereas there was a significant decrease (p

Effects of recovery time on phosphocreatine kinetics during repeated bouts of heavy-intensity exercise

The purpose of this study was to examine the kinetics of phosphocreatine (PCr) breakdown in repeated bouts of heavy-intensity exercise separated by three different durations of resting recovery. Healthy young adult male subjects (n = 7) performed three protocols involving two identical bouts of heavy-intensity dynamic plantar flexion exercise separated by 3, 6, and 15 min of rest. Muscle high-energy phosphates and intracellular acid-base status were measured using phosphorus-31 magnetic resonance spectroscopy. In addition, the change in concentration of total haemoglobin (Delta[Hb(tot)]) and deoxy-haemoglobin (Delta[HHb]) were monitored using near-infrared spectroscopy. Prior exercise resulted in an elevated (P < 0.05) intracellular hydrogen ion ([H(+)](i)) after 3 min (182 +/- 72 (SD) nM; pH 6.73) and 6 min (112 +/- 19 nM; pH 6.95) but not after 15 min (93 +/- 8 nM; pH 7.03) compared to pre-exercise in Con (90 +/- 3 nM; pHi 7.05). The on-transient time constant (tau) of the PCr primary component was not different amongst the exercise bouts. However, in each of the subsequent bouts the amplitude of the PCr slow component, total PCr breakdown, and rise in [H(+)](i) were reduced (P < 0.05). At exercise onset, Delta[Hb(tot)] was increased (P < 0.05) and the Delta[HHb] kinetic response was slowed (P < 0.05) in the exercise after 3 min, consistent with improved muscle perfusion. In summary, neither the level of acidosis or muscle perfusion at the onset of exercise appeared to be directly related to the time course of the on-transient PCr primary component or the magnitude of the PCr slow component during subsequent bouts of exercise.

Use of single photon counting detector arrays in combined PET/MR: Characterization of LYSO-SiPM detector modules and comparison with a LSO-APD detector

We propose in this study a novel PET detector concept asinsert for simultaneous PET/MR imaging, using arrays of SiliconPhotomultipliers (SiPMs) as photodetectors, read out by a dataacquisition system based on sampling ADCs. A 2 × 2 LSO-SiPMdetector array and four single channel LYSO-SiPM detectors have beenevaluated and compared to a LSO-APD detector. A 17.9% energyresolution and a 1.4 ns time resolution have been measured. Nodegradation of these values could be detected when simultaneous MRacquisitions were performed. The non-linear detector behaviour due tothe limited dynamic range and recovery time effects has beenstudied. In addition, the contribution of dark counts and opticalcrosstalk for PET applications was also addressed. The feasibility forposition localization of the incident light to a SiPM array usingAnger logic has been investigated.

The effect of recovery time and test conditions on viscoelastic measures of tensile damage in cortical bone

Stiffness degradation and strength degradation are often measured to monitor and characterize the effects of damage accumulation in bone. Based on evidence that these properties could be affected by not only damage magnitude but also test conditions, the present study investigated the effect of hold condition and recovery time on measures of tensile damage. Machined human femoral cortical bone specimens were subjected to tensile tests consisting of a pre-damage diagnostic loading cycle, a damage loading cycle and post-damage cycle. Controlled variables were recovery time (1, 10, and 100 min) and hold condition (zero load or zero strain) after the damage cycle. Damage measures were calculated as the ratio of each post-damage cycle to the pre-damage value for loading modulus, secant modulus, unloading modulus, stress relaxation and strain (stress) recovery at 1 min post-diagnostic time. The damage cycle caused reductions in all measures, and some measures varied with recovery time and hold condition. Apparent modulus degradation for both hold conditions decreased with recovery time. Stress relaxation was unaffected by recovery time for both hold conditions. Zero-strain hold conditions resulted in lower values for degradation of modulus and change of relaxation. Stress or strain recovery after the damage cycle was evident through 100 min, but 90% of the recovery occurred within 10 min. The results demonstrate that choice of test conditions can influence the apparent magnitude of damage effects. They also indicate that 10 min recovery time was sufficient to stabilize most measures of the damage state.

Effects of exposure duration and recovery time during pulsed exposures

In pulsed toxicant exposures, the concentration, duration, and frequency of pulses can change through time. However, the conventional median lethal concentration (LC50) method cannot adequately predict the effects of pulsed exposure, because it is associated with fixed exposure duration and constant concentration and does not include postexposure (latent) mortality. Many studies that tried to address the effects of pulsed exposure only provided qualitative or semiquantitative predictions. Survival time experiments conducted here quantified the effect of exposure duration on latent mortality, and the effect of recovery time between two pulses on mortality during a second pulse also was examined. This was done by exposing amphipods (Hyalella azteca) to two contrasting toxicants, copper sulfate (CuSO4) and sodium pentachlorophenol (NaPCP). In the exposure duration experiments, the amphipods were exposed to two toxicant concentrations for three durations. No significant effect of duration on latent mortality was detected within the experimental range; however, duration still may need to be considered under other conditions. In the recovery time experiments, the amphipods were provided four recovery times, and their survivals during the second exposure were modeled. Recovery time had a significant effect on the second-exposure mortality. Given enough time, the amphipods could recover to a state similar to their original toxicant resistance state. The complete recovery time for CuSO4 was fivefold longer than that for NaPCP. It is important to quantify the effects of latent mortality, pulse duration and concentration, and recovery time for pulsed exposures. Survival analysis provides a better way to address these issues than does the conventional LC50 method.

High strain-rate impact studies of predamaged rocket propellants. I. Characterization of damage using a cumulative damage failure criterion

The effect of predamage on the high strain-rate behavior, ignition sensitivity, and impact ignition mechanism of a HTPB/AP rocket propellant was assessed using a modified Hopkinson Bar. Damage was induced by constant stress and monotonic tension tests prior to testing on the modified Hopkinson Bar. Predamage was characterized using a failure criterion based on a linear Cumulative Damage model. Creep and recovery experiments were conducted to determine the amount of recovery (due to relaxation or viscoclastic effects) and rehealing of damage (nonrecoverable strain), and the effect of recovery time on the induced mechanical damage. The effect of residual void volume on the impact ignition sensitivity and mechanism for freshly damaged, rehealed, and undamaged propellant samples was also investigated.

A new model of shouldered survival curves.

Recently, the linear-quadratic equation has been used to construct the dose-response relationships of ionizing radiation. The radiobiological theory on which this relationship is based indicates that at low doses, the risk of a biological lesion being formed should depend linearly on dose if a single event is required or quadratically on dose if two events are required. The same approach has also been used to construct the shouldered survival curves, which indicate a lower response of cell killing at low doses of low linear energy transfer (LET) radiation than at high doses because of repair. However, a different approach is possible, derived from the concept of generating the hybrid lognormal distribution, in which the hybrid form of linear and logarithmic components of a random variable is used. The hybrid form is a formulation of the phenomenon in which there is a feedback mechanism against the large change in the random variable. This paper presents a new model of shouldered survival curves, called a hybrid scale model, which has two parameters: the inactivation constant and the protective factor. In the model, the surviving fraction, normalized by a protective factor plotted in a hybrid scale, is assumed to be linear against the dose. This simple model provides an implication of the shoulder of survival curve and the effect of recovery time of radiation damage, as well as giving a good to the well-known data of split-dose experiments with mammalian cells.

Problems in measuring human leucocyte cation content: effects of cell preparation and handling.

1. Previous published measurements of leucocyte cation content are inconsistent, with sodium concentrations having particularly high coefficients of variation. We have measured the effects of recovery time after isolation, different types of handling, and centrifugation on leucocyte sodium and potassium content. 2. Sodium content fell markedly during the first 30 min after isolation and was stable from 1 to 3 h of incubation. There was a small but significant rise in potassium content over the same time period. 3. During incubation, occasional gentle resuspension of the cells gave optimal sodium contents, whereas mixing by inversion caused large falls in sodium and potassium content. 4. Centrifugation of stable cells at 200 g for 6 min caused marked increases in sodium content.

Feeding reduction and recovery in cunner Tautogolabrus adspersus following exposure to crude oil.

In an actual oil spill situation exposure is usually short and at low hydrocarbon concentrations. Except for study organisms from an oil spill area very little work has been published on the effects of recovery time for feeding in oil-exposed fish. This study was initiated to determine the time course of the onset of feeding reduction and recovery under environmentally realistic conditions experienced during an oil spill.

Effect of hyperbaric oxygen exposure on pulmonary clearance of 5-hydroxytryptamine

Clearance of 5-hydroxytryptamine (5-HT) by the lungs of normal and vitamin E-deficient rats was evaluated following a 60-min exposure to 100% oxygen (O2) at 4 ATA (HBO). After exposure, lungs were isolated, ventilated, and perfused, with a recirculating system used for measurement of 5-HT clearance. Control lungs were obtained from rats exposed to air at 1 ATA. In control normal rats, fractional clearance of 5-HT was 0.78+/-0.03 (mean+/-SE). Following HBO 5-HT clearance was 0.55+/-0.04 (P less than 0.01). In control vitamin E-deficient rats. 5-HT clearance was 0.85+/-0.05 and was decreased to 0.46+/-0.03 (P less than 0.001) following HBO. To evaluate the effect of recovery time after HBO on 5-HT clearance, separate groups of rats were killed at varying intervals post-HBO. In normal rats, 5-HT clearance had returned to control levels by 3-4 after HBO; in vitamin E-deficient rats, clearance remained unchanged 4 h after HBO and was only 74% (P less than 0.001) of control values 24 h post-HBO. These results indicate that depression of pulmonary 5-HT clearance occurs in rats due to hyperoxia and is potentiated by vitamin E deficiency. This represents a reversible alteration of lung function which requires vitamin E for complete recovery.

Modification of the TRAC Ebers-Moll Model for Improved High Frequency and Collector Storage Time Predictions

The present TRAC Ebers-Moll model is modified in order to obtain an improved high frequency prediction. This is achieved by means of a three lump Linvill model to account for diffusion transport of minority carriers in the base region of a bipolar transistor. The modified Ebers-Moll model obtained in this manner yields two pole representations for the transport factors in the frequency domain. The two pole representation for hfe is shown to give reasonable fit both in amplitude and phase with experimental data obtained from a low frequency bipolar transistor, while the phase correlation obtained with the single pole representation of the present TRAC Ebers-Moll model is unsatisfactory, especially, at high frequencies. The present TRAC Ebers-Moll model was also modified so as to obtain an improvement in collector storage and recovery time prediction. This was accomplished by the introduction of two Linvill lumps in the collector region to account for minority carrier storage and transport. The observed experimental collector-base diode turn-off transient response for the same low frequency bipolar transistor was found to be in agreement with the prediction of the modified model. Finally, the paper is concluded with a discussion of a modified model to account for both the high frequency response, as well as, collector storage and recovery time effects.

Effect on Auditory Functioning of Repeated Exposure to Temporary Fatigue

The experiments reported assess (1) the effect of repeated high-intensity stimulation on the threshold of audition and on intensity discrimination and (2) the effect of recovery time on intensity discrimination, holding degree of TTS constant. The first experiment exposed Ss to a 2-Kc-sec tone presented at 105 dB SL for 2 min. Pre- and post-exposure measurements of the threshold of audition and intensity discrimination were obtained for 20 sessions. The second experiment varied the duration and level of the high-intensity fatiguing stimulus so that a given TTS (10 or 20 dB) could be obtained at a specific time period after exposure. Pre- and post-measurements of intensity discrimination were obtained. The results showed a trend, possibly indicative of learning, toward a lower pre- and post-exposure threshold—but this trend was not supported statistically. Consequently, it can be concluded that repeated high-intensity stimulation similar to that in the experiment did not result in any systematic shift in sensitivity. Additionally, it appears that the degree of TTS is the determiner of any change that occurs in intensity discrimination, rather than the time of recovery at which the measurement is obtained.

On Some Transients in the Pulse Response of Point-Contact Germanium Diodes

Several recovery time effects in germanium point contact diodes are described and a hypothesis is proposed to explain the observed effects. This hypothesis postulates the presence of traps in the germanium p layer near the point electrode. Measurements and computations based on this hypothesis give trap densities of the order of 1016/cm3, trap depths in the energy band of the order of 0.3 electron volts, and capture cross-section diameters for the traps of the order of 0.3 Å.